The present invention relates to methods for producing chewing gum. More particularly, the invention relates to methods for producing chewing gum containing acetals of cinnamaldehyde and peptide sweeteners with improved shelf-life stability.
In recent years, efforts have been devoted to protecting high-potency sweeteners within the chewing gum formulation from interaction in the presence of aldehyde ingredients, i.e., the protection of the high-potency sweetener against degradation over time. The instability is significant because aldehyde-containing flavor components such as cinnamaldehyde found in cinnamon oil have been known to react with the aspartame and thereby greatly reduce the shelf-stability of aspartame in such a gum.
For example, U.S. Pat. Nos. 4,722,845, issued Feb. 2, 1988, and 4,839,184, issued Jun. 13, 1989, both to Cherukuri et al., teach a process for stabilizing cinnamon-flavored chewing gum in which a dipeptide or amino acid sweetener is encapsulated in a mixture of fat, wax and glyceride. The inventions teach an advantage in using an edible wax with a melting point of 106.degree. C. or greater. First, the fat, wax and glyceride are mixed to form a "hydrophobic matrix." Then, the sweetener is formed into an agglomerate with this hydrophobic matrix. The agglomerates are next screened for appropriate size. Finally, the second or further coating with the hydrophobic matrix is applied using standard fluidized bed granulation techniques. Alternately, the initial coating can be applied by spray congealing techniques. Both of the above Cherukuri et al. patents teach that aspartame is difficult to coat, because of its needle-like shape. To adequately coat aspartame, approximately six times as much coating material as aspartame was used.
U.S. Pat. No. 4,863,745, issued Sep. 5, 1989, to Zibell, teaches a method of encapsulating aspartame or other high-potency sweeteners by applying to already-coated aspartame a second coat consisting predominately of zein, a corn protein. This method results in more gradual release of high-potency sweetness and in protection from degradation by aldehyde constituents.
U.S. Pat. No. 4,931,295, issued Jun. 5, 1990, to Courtright et al., discloses the preparation of a softer zein coating for aspartame which is water soluble and includes water-soluble cellulose. Courtright discloses that encapsulation and protection from degradation occurs when the final product comprises as little as 10% zein.
Examples of aldehyde-containing flavoring agents include, but are not limited to, cinnamon oil, which includes cinnamaldehyde; cherry flavor, which includes benzaldehyde; lemon flavors which contain citral and citronellal; vanilla flavor, which includes vanillin and ethyl vanillin; fruit flavor, which includes acetaldehyde; and orange flavor, which includes undecanal. Other flavors which include aldehyde containing components can be found on pages 325-328 of the book Flavor Technology: Profiles, Products, Applications, by Henry B. Heath, M.B.E., B. Pharm., published in 1978 by The AVI Publishing Co., Inc., Westport, Conn. The most popular aldehyde-containing flavor used in chewing gum is a cinnamon flavor, which includes cinnamaldehyde.
Cinnamic aldehyde is the primary ingredient in cinnamon flavoring. Cinnamic aldehyde also is used to enhance fruit and many other flavors. Cinnamic aldehyde has been added to a variety of foods, including gum. In chewing gum, however, the cinnamic aldehyde flavor reacts with peptide sweeteners to form non-sweet products. In addition, the cinnamon flavor dissipates after only a few minutes of chewing. Methods of preventing the dissipation of cinnamaldehyde, including the chemical combination of cinnamic aldehyde with other moieties, have been investigated.
Co-pending, commonly assigned, U.S. patent application Ser. No. 550,676, filed on Jul. 11, 1990, by Sonya Johnson and Michael Greenberg, entitled "Method of Prolonging Flavor in Chewing Gum by the Use of Cinnamic Aldehyde Propylene Glycol Acetal," discloses a novel chemical form of cinnamaldehyde (cinnamaldehyde propylene glycol acetal [CAPGA]), its use in gum, and methods for making the compound and for making gum and other foods.
On page 315 of West et al. "Synthetic Perfumes: Their Chemistry and Preparation," published by Edward, Arnold & Co., London, England, 1949, cinnamaldehyde dimethyl acetal is reported to "have a fine cinnamon-cassia odor which renders it useful in some Chanel-like fancy perfume and in oriental types like Tabac Blond and Fleur de Tabac." Cinnamaldehyde diethyl acetal also is discussed.
Cinnamaldehyde dimethyl acetal and diethyl acetal also were mentioned in the definitive work "Perfume and Flavor Chemicals (Aroma Chemicals)" by Steffen Arctander, privately published in Montclair, N.J. in 1969. The dimethyl acetal was described as practically colorless, carrying little or none of the odor with which the free aldehyde is associated. The diethyl acetal was described as having a "faint but fresh green slightly spicy oily sweet odor and a mild and oily sweet taste" (Page 620). Arctander judged the diethyl acetal to be of little value in flavoring because like most other acetals, the diethyl acetal was unstable under mildly acid conditions.
Arctander reported on cinnamaldehyde-2,4-dihydroxy-4-methyl-pentane acetal, describing it as having a "soft, tenacious, natural, cinnamon-type odor, not nearly as harsh as cinnamic aldehyde itself" (Page 621).
Arctander also reported on cinnamaldehyde ethylene glycol acetal, describing it as having a "sweet-spicy cinnamon-allspice taste, but not quite as sweet as the aldehyde" (Page 623). Arctander indicated that this latter acetal would be useful in flavor compositions, including all-spice, cassia, cinnamon, clove and various spice blends.
These cinnamaldehyde acetals were recognized as relatively unstable, especially in aqueous media, and thus were considered undesirable as perfume or flavor ingredients.
Acetals have been combined with other flavor chemicals to produce longer-lived chemicals. U.S. Pat. No. 3,898,283, issued Aug. 5, 1975, to Schreiber et al., teaches methods to produce phenyl pentenals, as well as their acetals.
U.S. Pat. No. 3,908,023, issued Sep. 23, 1975, to Schreiber et al., further teaches the production of cinnamon-like flavors with phenyl pentenals and their acetals. However, Schreiber points out that these chemicals are very stable, only hydrolyzing under "intense hydrolytic conditions" (col. 2, line 66). These conditions include a pH which is less than 2.5 or greater than 11.5, far different from the relatively neutral pH of saliva. This reference also teaches that 1,2- and 1,3-propylene glycol may be used in acetals to stabilize phenyl pentenals (col. 6, line 13).
U.S. Pat. No. 3,879,425, issued Apr. 22, 1975, to Hall et al., teaches that 3-phenyl-4-pentenal ethylene acetal is a stable precursor for the aldehyde, which has a green floral fragrance. It teaches that a variety of phenyl pentenals, can be combined with a variety of acetals. A list of such acetals includes propylene glycol acetal (col. 9, lines 50-51).
U.S. Pat. No. 4,571,344, issued Feb. 18, 1986, to Pittet et al., teaches preparation of a sustained release flavor by combining dithioethers of phenyl alkenals with silica and propylene glycol (cols. 23 and 24). Pittet also teaches using the silica mixture in chewing gum (col. 24, lines 43-54). Pittet also reports long-lasting flavor with the dithioether flavor alone (col. 24, lines 58-64).
Unfortunately, a disadvantage of all techniques for preventing peptide sweeteners from interacting with aldehyde compounds is that they call for encapsulating the sweetener. The more effective techniques for encapsulating the sweetener require long drying periods and coating the sweetener at least twice, an expensive process. Even then, the peptide sweetener is not always fully protected. What is needed is less expensive and more convenient protection of peptide sweeteners from chemical degradation by aldehyde compounds.